Method of making a dynamoelectric machine conductor bar and method of making a conductor bar dynamoelectric machine, the bar and the machine

ABSTRACT

A method for making a dynamoelectric machine conductor bar, compromises providing a plurality of bundled together spiraling strand conductors having surrounding insulation to define a substantially rectangular shape with the strand conductors and strand insulation defining an opposing conductor bar end portion having an electrically insulated gap between the strand insulation adjacent the bar end portion; and applying a filler material to fill the gap to electrically shield the conductor bar end portion and to a greater than 0.080 to about 1.5 inch continuous outer radius surface end portion. A dynamoelectric machine conductor bar comprises a plurality of bundled together spiraling strand conductors having surrounding insulation to define a substantially rectangular shape, with the strand conductors and strand insulation defining an opposing conductor bar end portion; an electrically non-insulated gap between the strand insulation adjacent the conductors at the bar end portion; and an applied filler material filling the gap to electrically shield the conductor bar end portion an applied filler material filling the gap to electrically shield the conductor bar end portion, wherein the filler material defines a greater than 0.080 to about 1.5 inch continuous outer radius surface end portion.

BACKGROUND OF THE INVENTION

[0001] The invention relates to a high voltage electrical windingconductor bar for use in a dynamoelectric machine. In particular, itrelates to stator bars used in generators where the bars comprisestrands of conductors bundled together, insulated from each other bystrand insulation and additionally surrounded by groundwall insulation.

[0002] The thickness of stator bar groundwall insulation is a limitingfactor in an electrical generator stator bar design and in machineoutput. If the thickness of the groundwall insulation can be reduced,more space would be available for conductors in the same slot. As aresult, the size of the conductors can be increased thereby increasingconductor volume and current capacity for the same size bar.Alternately, the bar size could be decreased with no loss in conductorvolume, resulting in reduced machine size with associated weight andmaterial cost savings.

[0003] Presently, high voltage stator bars are constructed by bundling anumber of conductors of copper or aluminum strands that are insulatedfrom each other by strand insulation. The strands of insulation arecommonly arranged to form two tiers that can be separated by a strandseparator. Alternatively, the stator bar can be constructed withfour-tier and six-tier strands. The strands can be arranged in aspiraling manner, also known as Robeling. Top and bottom edge unevensurfaces are created where spiraling conductor strands cross over fromone tier to a next tier along the slot length. The conductor bar endscan be leveled or evened by molding a transposition filler to the endsduring pressing of the conductor package.

[0004] A groundwall insulation can be provided by multiple wrappings ofa mica paper tape surrounding the tier strands, strand insulation andtransposition filler. The amount of insulation is dependent on thecapability of the insulation to survive corner electrical stressconcentration. Sharp corners concentrate electrical stress whileconductor corner increased radius reduces stress. The generalrectangular geometry of a stator bar results in high corner electricalstress.

[0005] It is desirable to reduce corner electrical stress. A reductionin electrical stress can result in a reduction in the amount ofgroundwall insulation, which can allow for additional space forconductors. Or a reduction in corner stress can increase a voltagerating of a dynamoelectric machine by providing generator stator barsthat can operate at higher nominal voltage stress. Typically, cornerstress is reduced by machining or shaving of strand corners. However,machining decreases strand copper content. Reduction in copper contentreduces conductivity. Hence, the strands are machined or shaved only ator near their corners. Typically the copper cross-section in each strandspiraling is reduced up to 0.080 inch, usually 0.060 to 0.080 inch alongthe bar and typically only at one corner of each strand. Reductiongreater than 0.080 inch can result in hot spots or leaks in hollowliquid cooling stator bars.

[0006] Hence, there is a need to effectively reduce voltage stressconcentration by increasing radius at conductor bar surface cornerswithout significantly decreasing strand copper or aluminum content.

SUMMARY OF THE INVENTION

[0007] The invention provides a method for making a dynamoelectricmachine conductor bar suitable for use in a dynamoelectric machine. Thebar has reduced corner stress that is achieved, surprisingly withoutdecreasing strand copper or aluminum content. The method comprisesproviding a plurality of bundled together spiraling strand conductorshaving surrounding insulation to define a substantially rectangularshape with the strand conductors and strand insulation defining aconductor bar end portion having an electrically insulated gap betweenthe strand insulation adjacent the conductor bar end portion; andapplying a filler material to fill the gap to electrically shield theconductor bar end portion and to define a greater than 0.080 inchcontinuous outer radius surface end portion.

[0008] In another embodiment, the invention is a method for making adynamoelectric machine having a stator with a high voltage windingcomprising a plurality of conductor bars extending along slots in thewinding, comprising: providing a plurality of bundled together spiralingstrand conductors having surrounding insulation to define asubstantially rectangular shape, with the strand conductors and strandinsulation defining a conductor bar end portion having an electricallyinsulated gap between the strand insulation adjacent the bar endportion; and applying a filler material to fill the gap to electricallyshield the conductor bar end portion and to define a greater than 0.080inch continuous outer radius surface end portion.

[0009] The invention also relates to a high voltage electrical windingconductor bar suitable for use in a dynamoelectric machine. Thedynamoelectric machine conductor bar comprises a plurality of bundledtogether spiraling strand conductors having surrounding insulation todefine a substantially rectangular shape with the strand conductors andstrand insulation defining an opposing conductor bar end portion; anelectrically non-insulated gap between the strand insulation adjacentthe conductors at the bar end portion; and an applied filler materialfilling the gap to electrically shield the conductor bar end portion anapplied filler material filling the gap to electrically shield theconductor bar end portion, wherein the filler material defines a greaterthan 0.080 to about 1.5 inch continuous outer radius surface endportion.

[0010] In another embodiment, the invention is dynamoelectric machinehaving a stator with a high voltage winding comprising a plurality ofconductor bars extending along slots in the winding, the conductor barscomprising: a plurality of bundled together spiraling strand conductorshaving surrounding insulation to define a substantially rectangularshape, with the strand conductors and strand insulation defining anopposing conductor bar end portion; an electrically non-insulated gapbetween the strand insulation adjacent the conductors at the bar endportion; and an applied filler material filling the gap to electricallyshield the conductor bar end portion, wherein the filler materialdefines a greater than 0.080 to about 1.5 inch continuous outer radiussurface end portion.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The invention can be appreciated from the detailed description inconnection with the accompanying drawings wherein:

[0012]FIG. 1 is a cut away view of a prior art conductor bar for use ina high voltage winding of a generator;

[0013]FIG. 2 is a cut away view of a conductor bar according to theinvention for use in a high voltage winding of a generator;

[0014]FIG. 3 is a view of a strand utilized in the conductor barillustrating Roebeling or spiraling of the strands;

[0015]FIG. 4 is an end view showing the placement of the conductor barsas winding in slots in the generator;

[0016]FIG. 5 illustrates the increased radius of the conductor bar priorto the application of the groundwall insulation;

[0017]FIG. 6 illustrates the increased radius as a variable radius ofthe conductor bar prior to the application of the groundwall insulation;

[0018]FIG. 7 illustrates the increased radius as a full round radius ofthe conductor bar prior to the application of the groundwall insulation;and

[0019]FIG. 8 is a cut away side schematic view of an dynamoelectricmachine showing the location of a conductor bar.

DETAILED DESCRIPTION OF THE INVENTION

[0020] The conductor bar of the invention has a filler material thatfills a gap that is defined between a substantially rectangular shapedbundle of strand conductors and surrounding insulation. Without thefiller material, the abrupt corner angles of the relatively squarecorners of the rectangular stator cause stress concentrations on appliedground insulation. The filler material modifies the strand conductorouter radius surface to reduce this stress. The filler material can beapplied to both top and bottom bar ends. Using filler materialeliminates bar corner shaving and hence avoids reducing the bar copperor aluminum content.

[0021] Modifying the bar with filler material provides an increasedconductor package surface corner radius, which reduces bar cornerelectrical stress. The invention can be used in combination withinternal grading to further reduce bar corner electrical stress. Areduction in corner stress means that less ground insulation material isrequired to insulate the strand conductors. Less insulation improvesheat transfer across the thinner groundwall insulation to the machinecore. Also, reduction in ground insulation material means thatadditional space is available for copper conductors that can improvegenerator performance.

[0022] The filler material modified corner can provide a continuousouter surface corner radius. In an embodiment, the continuous radius isat least greater than 0.080 inches or in ranges of at least greater than0.080 to 1.5 inches continuous outer radius surface, desirably 0.1 to0.875 inches and preferably 0.125 to 0.75 inches continuous outer radiussurface. The continuous surface corner radius is a surface of curvaturetranscribed by common radius line segments at the bar end portion asshown in FIG. 3.

[0023] Alternatively, the outer surface can be in an elliptical shapewith a variable radius. The variable radius can fall in the range of0.080 to 0.875 inches. In another alternative, the top edges of thefiller material can be relatively flat with the corner radius of thefiller material adjacent the conductor bar ends being greater than about0.125 inches. The corner configurations of the invention impart improvedreduced stress concentration to generally rectangular conductors.

[0024] In one embodiment, a fillet material is applied to the endportion to provide the enlarged outer radius surface. In this manner,the radius surface is enlarged without substantial loss of conductorcross-section material. Both top and bottom bar edges can be modified.Modifying the bar with a fillet material on top and bottom edges incombination with internal grading reduces electrical stressconcentration on corner ground insulation. Hence, less insulation may berequired and more space can be made available for copper conductors.

[0025] Internal grading can be provided to the filler material so thatan equal potential voltage plane on the filler material larger radiiouter surface results in the stress reducing benefits on the groundinsulation. The internal grading can impart a resistivity in the rangeof 500 to 500,000 ohms per square, desirably 1,000 to 250,000 andpreferably 2,000 to 100,000 ohms per square. For example, internalgrading or low conductivity can be provided by the following:

[0026] Application of a low conductivity paint. Preferably, the lowconductivity paint has a resistance in the range of 2,000 to 100,000ohms per square in its cured state. The paint is applied intoelectrically conducting relation with the electrically non-insulated gapportions in the strand insulation. The paint can be applied on the topand bottom edges or across the conductor bar end portions of the bar.

[0027] Application of a low conductivity transposition filler. The lowconductivity transposition filler can have a resistance in the range of2,000 to 100,000 ohms per square in its cured state. It can be appliedto conductor bar end portions during molding.

[0028] Wrapping of a low conductivity tape. The tape can have aresistance in the range of 2,000 to 100,000 ohms per square in its curedor dry state. The tape can be applied around the bar before thegroundwall insulation is applied.

[0029] Alternately conductive filler strips. The strips can have aresistance in the range of 2,000 to 100,000 ohms per square. The stripscan be molded or glued onto conductor package ends. Conductivefiberglass filler strips with correct resistively can be used.

[0030] The filler material can comprise a non-conductive thermosetmaterial such as a putty made from an epoxy or polyester resincontaining mica powder, mica paper, silica or other fillers. The fillermaterial can also comprise a conductive non-metallic material such as athermoset epoxy or polyester resin containing conductive carbon orgraphite fillers. The filler material can be made of conducting ornon-conducting laminated material, such as woven fiberglass treated withan epoxy or polyester resin.

[0031] The filler material can be molded onto the bar when the conductorpackage is pressed and cured during forming. Alternatively, a regularrectangular bar can first be pressed to shape and the filler materialapplied to the top and bottom bar corners. It is also possible to use aRoebel transposition filler such as a catalyzed epoxy resin filler onthe bars together with a fillet strip, applied prior or subsequent topressing. A thick layer of transposition filler can be molded onto thebar so that molded transposition filler extends above the uppermoststrand and below the bottom-most strand. After molding, the corners canbe machined to a desired radius. Also, mold tooling can be used to formthe corner radius during a pressing operation.

[0032] These and other features will become apparent from the drawingsand following detailed discussion, which by way of example withoutlimitation describe preferred embodiments of the invention. In thedrawings, corresponding reference characters indicate correspondingparts throughout the several figures.

[0033]FIG. 1 shows a prior art electrical conductor bar 10. In FIGS. 2and 4, electrical conductor bar 10 is insulated according to the presentinvention. In FIGS. 1 to 3, the conductor bar 10 has a plurality ofbundled together spiraling strand conductors 12. The strand conductorsare also known as turns or turn conductors. The strand conductors 12 arespiraled in a manner referred to as Roebeling, shown more specificallyin FIG. 3. The bars shown in FIGS. 1 to 3 are one-turn bars made up of anumber of individual strands. The strands are individually insulatedfrom one another by strand insulation 14 and are Roebeled to reduceelectrical losses within the bar. Typically, the strand conductorscomprise either an aluminum or copper material and portions of thestrand insulation 14 are removed at 16 adjacent conductor bottom and topbar end portions.

[0034] Strand conductors 12 and strand insulation 14 define opposingbottom and top conductor bar end portions 18. As shown in FIG. 1, thecorner radius at the end portions 18 defines a generally rectangularshape d structure. This corner radius is typically in the order of 0.031inches and is less than 0.080 inches. The strand conductors 12 arearranged in two side-by-side columns or tiers 15. While FIGS. 1 to 3show two tiers 15, the strands can be arranged in any number of tierssuch as for example four-tiers or six-tiers. Between each tier 15 is aseparator insulation 17.

[0035]FIGS. 2 and 4 show a conductor bar 10 with applied filler material24. The material has been applied across the conductor bar end portions18. The filler material 24 fills void area 26 that is defined by thespiraling of the strand conductors 12. The filler material 24 can beconducting and can function as internal grading. On the other hand, thefiller material 24 can be non-conducting in which case, internal gradingcan be applied. In the non-conducting case, the filler material can havean electrically conductive paint applied to outer surface 28. In FIGS. 2and 4, outer surface 28 has a surface corner radius at greater than 0.08inches. At least the outer surface 28 of the filler material 24 is inelectrical conducting relation with the electrically non-insulated gapportions 16 to electrically shield the conductor bars 10 at theconductor bar end portions 18.

[0036] A groundwall insulation layer 30 in the form of a mica based tapesurrounds the plurality of strand conductors 12 and the filler material24 (in the cases of FIGS. 2 and 4). The groundwall insulation layer 30follows the shape or radius of the conductor bar end portions 18. As aresult, the groundwall insulation has rounded corners 32 in FIG. 2 andFIG. 4 and substantially square corners 34 in FIG. 1.

[0037] Further in FIG. 4, two conductor bars 10 are located within slots40 of the core 42 of a winding of a generator. The slots are filled withnon-conducting fillers 44 extruded in a half bow-tie shape. A wedge 46assists to maintain the conductor bars 10 within the slots 40 of thecore 42 of the high voltage winding.

[0038] In FIG. 5, the filler material 24 is formed onto the conductorbar end portions without the removal of any copper from the strandconductors 12. The corners 20 of the filler are in the range of 0.125 to0.275 inches and have a flat portion 21 between corners 20.

[0039] In FIG. 6, the filler material 24 is formed onto the conductorbar end portions without the removal of any copper from the strandconductors 12. The corners 20 of the filler material are in the range ofgreater than or equal to 0.275 inches and the portion 23 of the filerbetween the corners has a variable radius.

[0040] In FIG. 7, the filler material 24 is formed onto the conductorbar end portions to form rounded edges without requiring removal of anycopper. In this instance, the corners 20 and middle portion 25 are ofthe same radius, which is about 0.875 inches.

[0041]FIG. 8 shows a dynamoelectric machine 50 showing the location ofrotor 54 and conductor bar 10 including conductor core 52. The machine50 includes generator frame 56 and top stator bar 58 and bottom statorbar 60.

[0042] The following EXAMPLES are illustrative and should not beconstrued as a limitation on the scope of the claims unless a limitationis specifically recited.

[0043] Voltage breakdown strength of an insulated stator bar is ameasure of insulation quality and long term stability of the insulationwhen stressed at lower operating voltages. In the EXAMPLES, insulatedstator bars were tested for breakdown strength immersed in oil toprevent flashover during testing. The test was started at 30,000 volts,60 Hertz and held 60 seconds at that voltage. The voltage was thenincreased to 35,000 volts and held for 60 seconds. The voltage wasraised in increments of 5,000 volts per 60-second steps until breakdownoccurred. Breakdown voltage is equal to (highest voltage)−5000+[(5000volts)×(seconds at the highest voltage/60 seconds)]. Breakdown strengthin units of VPM (volts per mil) is the breakdown voltage/smallestaverage insulation thickness on the side of a bar in mils.

EXAMPLE 1

[0044] Stator bars having 0.060- to 0.080-inch corner radii wereinsulated with a mica tape containing mica paper and glass fabricbacker. The resin binder for the tape was based on U.S. Pat. No.5,618,891. Internal grading was applied using a glass fabric tape. Thebreakdown strength of these bars was 874±44 VPM.

EXAMPLE 2

[0045] A 0.090-inch thick glass-epoxy strip was bonded to the top andbottom edges of a bare bar having the same dimensions as those used inEXAMPLE 1. The corners were then machined to 0.15-inch radii. The barwas internally graded with the same glass tape and taped with the samemica tape used in EXAMPLE 1. The same number of mica tape layers wasused. The voltage breakdown strength of this bar was 1,017 VPM.

EXAMPLE 3

[0046] A 0.060-inch thick glass-epoxy strip was bonded to the top andbottom edges of a bare bar having the same dimensions as those used inEXAMPLE 1. The bar corners were then machined to 0.15-inch radii. Thebar was internally graded with the same tape used and taped with thesame mica tape used in EXAMPLE 1. The same number of mica tape layerswas used. The voltage breakdown strength of this bar was 1,024 VPM.

EXAMPLE 4

[0047] Long term voltage endurance tests were conducted. The baselinegroundwall insulation system described in EXAMPLE 1 using stator barshaving corner radii of 0.060 to 0.080-inch was tested at differentvoltage stress levels in order to determine endurance life as a functionof voltage stress. Based on a statistical distribution oftimes-to-failure for this baseline group, a mathematical expression wasdeveloped to establish a baseline performance value.

EXAMPLE 5

[0048] The performance of individual stator bars were subsequentlytested under identical conditions but with corner radii greater than0.080-inch. For convenience, voltage endurance performance of individualexperimental bars is expressed in per unit of the median life expectancyfor the baseline insulation having corner radii from 0.060 to 0.080inch.

[0049] A bar identical to those in EXAMPLE 4 was modified by bonding a0.060-inch thick epoxy-woven glass laminate to its top and bottom edges.The laminate was bonded with a solvent-less epoxy adhesive. After theepoxy adhesive cured, the corners of the bar were machined to 0.15-inchradii. The bar was insulated with the same mica tape used in the EXAMPLE4 bars. The insulated bar was tested for voltage endurance at 40 kV. Thebar did not fail even after exceeding the median life of the bars ofEXAMPLE 4 by a factor of 1.62.

EXAMPLE 6

[0050] Another bar was made that had the same bare bar modifications asthe bar in EXAMPLE 5. The bar was insulated with the same mica tape usedin EXAMPLE 4. The bar was tested for voltage endurance at 40 kV. Thisbar did not fail even after exceeding the median life of the bars ofEXAMPLE 4 by a factor of 1.40.

[0051] The results for the EXAMPLES 5 and 6 bars were 62% and 40%respectively better than the baseline results of EXAMPLE 4.

[0052] The voltage breakdown strength and voltage endurance tests ofEXAMPLES 2, 3, 5 and 6 for increased radii bars show the superiorperformance and improved resistance to voltage stress concentration ofthe generator stator bars of the invention.

[0053] It should be understood that alternative embodiments of thepresent invention may be readily apparent to a person skilled in the artin view of the above description for the preferred embodiments of thisinvention. Accordingly, the scope of the present invention should not belimited to the teachings of the preferred embodiments and should belimited to the scope of the claims that follow.

What is claimed:
 1. A method for making a dynamoelectric machineconductor bar, compromising: providing a plurality of bundled togetherspiraling strand conductors having surrounding insulation to define asubstantially rectangular shape, with the strand conductors and strandinsulation defining an opposing conductor bar end portion having anelectrically insulated gap between the strand insulation adjacent thebar end portion; and applying a filler material to fill the gap toelectrically shield the conductor bar end portion and to define agreater than 0.080 inch continuous outer radius surface end portion. 2.The method of claim 1, further comprising surrounding the plurality ofstrand conductors and the filler material with a groundwall insulationlayer.
 3. The method of claim 1, comprising applying the filler materialto define an outer surface having a variable radius.
 4. The method ofclaim 1, comprising applying the filler material to define an outersurface corner radius adjacent the corners of the conductor end portionsin the range of 0.275 to 0.875 inches.
 5. The method of claim 1,comprising applying a fillet as the filler material, wherein the filletcomprises an electrically non-conducting material with an outer surfacethat comprises a low conductivity paint having a conductivity in therange of 2,000 to 100,000 ohms per square in its cured state.
 6. Themethod of claim 1, comprising applying the filler material to theconductor bar during a step of molding of the bar.
 7. The method ofclaim 1 wherein the filler material is a fillet that is wrapped aroundthe bar and the method further comprises taping groundwall insulationonto the bar subsequent to wrapping the fillet material.
 8. The methodof claim 1 wherein the filler material is a fillet that is wrappedaround the bar and the method further comprises taping groundwallinsulation onto the bar prior to applying the fillet.
 9. The method ofclaim 1, comprising applying the filler material and shaving to define agreater than 0.080 to 1.5 outer radius surface.
 10. The method of claim1, comprising applying the filler material to define a greater than0.080 to 1.5 outer radius surface without shaving.
 11. A method formaking a dynamoelectric machine having a stator with a high voltagewinding comprising a plurality of conductor bars extending along slotsin the winding, comprising: providing a plurality of bundled togetherspiraling strand conductors having surrounding insulation to define asubstantially rectangular shape, with the strand conductors and strandinsulation defining an opposing conductor bar end portion having anelectrically insulated gap between the strand insulation adjacent thebar end portion; and applying a filler material to fill the gap toelectrically shield the conductor bar end portion and to define agreater than 0.080 inch continuous outer radius surface end portion. 12.The method of claim 11, further comprising surrounding the plurality ofstrand conductors and the filler material with a groundwall insulationlayer.
 13. The method of claim 11, comprising applying the fillermaterial to define an outer surface having a variable radius.
 14. Themethod of claim 11, comprising applying the filler material to define anouter surface radius adjacent the corners of the conductor end portionsin the range of 0.275 to 0.875 inches.
 15. The method of claim 11,comprising applying a fillet as the filler material wherein the filletcomprises an electrically non-conducting material with an outer surfacethat comprises a low conductivity paint having a conductivity in therange of 2,000 to 100,000 ohms per square in its cured state.
 16. Themethod of claim 11, comprising applying the filler material to theconductor bar during a step of molding the bar.
 17. The method of claim11 wherein the filler material is a fillet that is wrapped around thebar and the method further comprises taping groundwall insulation ontothe bar subsequent to wrapping the fillet.
 18. The method of claim 11wherein the filler material is a fillet that is wrapped around the barand the method further comprises taping groundwall insulation onto thebar prior to wrapping the fillet.
 19. The method of claim 11, comprisingapplying the filler material and shaving to define a greater than 0.080to 1.5 outer radius surface.
 20. The method of claim 11, comprisingapplying the filler material to define a greater than 0.080 to 1.5 outerradius surface without shaving.
 21. A dynamoelectric machine conductorbar, comprising: a plurality of bundled together spiraling strandconductors having surrounding insulation to define a substantiallyrectangular shape, with the strand conductors and strand insulationdefining an opposing conductor bar end portion; an electricallynon-insulated gap between the strand insulation adjacent the conductorsat the bar end portion; and an applied filler material filling the gapto electrically shield the conductor bar end portion, wherein the fillermaterial defines a greater than 0.080 to about 1.5 inch continuous outerradius surface end portion.
 22. The dynamoelectric machine conductor barof claim 21, wherein the filler material defines a 0.10 to 0.875 inchcontinuous outer radius surface end portion.
 23. The dynamoelectricmachine conductor bar of claim 21, wherein the filler material defines a0.125 to 0.75 inch continuous outer radius surface end portion.
 24. Thedynamoelectric machine conductor bar of claim 21, further comprising agroundwall insulation layer surrounding the plurality of strandconductors and the filler material.
 25. The conductor bar of claim 21,wherein the filler material defines a variable outer radius surface. 26.The conductor bar of claim 21, wherein the filler material is aglass-epoxy strip.
 27. The conductor bar of claim 21, wherein the fillermaterial comprises an electrically non-conducting fillet and an outersurface of the fillet comprises a low conductivity paint having aconductivity in the range of 2,000 to 100,000 ohms per square in itscured state.
 28. The conductor bar of claim 21, wherein the fillermaterial is a fillet that is applied to the conductor bar duringmolding.
 29. The conductor bar of claim 21, wherein the filler materialis an electrically non-conducting fillet.
 30. The conductor bar of claim21, wherein the filler material is an electrically non-conducting filletthat is wrapped around the bar before the groundwall insulation is tapedon the bar.
 31. A dynamoelectric machine having a stator with a highvoltage winding comprising a plurality of conductor bars extending alongslots in the winding, the conductor bars comprising: a plurality ofbundled together spiraling strand conductors having surroundinginsulation to define a substantially rectangular shape, with the strandconductors and strand insulation defining an opposing conductor bar endportion; an electrically non-insulated gap between the strand insulationadjacent the conductors at the bar end portion; and an applied fillermaterial filling the gap to electrically shield the conductor bar endportion, wherein the filler material defines a greater than 0.080 toabout 1.5 inch continuous outer radius surface end portion.
 32. Thedynamoelectric machine of claim 31, wherein the filler material definesa greater than 0.080 to about 1.5 inch continuous outer radius surfaceend portion.
 33. The dynamoelectric machine of claim 31, wherein thefiller material defines a 0.10 to 0.875 inch continuous outer radiussurface end portion.
 34. The dynamoelectric machine of claim 31, whereinthe filler material defines a 0.125 to 0.75 inch continuous outer radiussurface end portion.
 35. The dynamoelectric machine of claim 31, furthercomprising a groundwall insulation layer surrounding the plurality ofstrand conductors and the filler material.
 36. The dynamoelectricmachine of claim 31, wherein the filler material defines a variableouter radius surface.
 37. The dynamoelectric machine of claim 31,wherein the filler material is a glass-epoxy strip.
 38. Thedynamoelectric machine of claim 31, wherein the filler materialcomprises an electrically non-conducting fillet and an outer surface ofthe fillet comprises a low conductivity paint having a conductivity inthe range of 2,000 to 100,000 ohms per square in its cured state. 39.The dynamoelectric machine of claim 31, wherein the filler material is afillet that is applied to the conductor bar during molding.
 40. Thedynamoelectric machine of claim 31, wherein the filler material is anelectrically non-conducting fillet.
 41. The dynamoelectric machine ofclaim 31, wherein the filler material is an electrically non-conductingfillet that is wrapped around the bar before the groundwall insulationis taped on the bar.